/*
 * (c) Copyright 2009 Hewlett-Packard Development Company, LP
 * All rights reserved.
 * [See end of file]
 */

package com.hp.hpl.jena.clusteredtdb.base;

import java.util.Iterator;

public class BufferedIterator<T> implements Iterator<T> {

	protected int bufSize;
	protected IteratorProcessor<T> worker;
	protected Iterator<T> buf1;

	//TODO implement remove, etc

	public BufferedIterator(int bufSize, IteratorProcessor<T> worker) {
		this.bufSize = bufSize;
		this.worker = worker;
	}

	@Override
    public boolean hasNext() {
		if (buf1 == null || buf1.hasNext() == false) {
			buf1 = worker.getChunk(bufSize);
		}
		return buf1.hasNext();
	}
	
	@Override
    public T next() {
		//ensures we've made an attempt to fill the buffer prior to calling next()
		if(this.hasNext()) {
			return buf1.next();
		} else {
			return null;
		}
	}

	@Override
    public void remove() {
	    throw new UnsupportedOperationException("BufferedIterator.remove") ;
		//unimplemented.  NOTE: would need to keep track of previous buffer to implement this
	}
	
}

/*
 * (c) Copyright 2009 Hewlett-Packard Development Company, LP
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
